Also four additional commands:
show; to prints all de?nitions on screen
save flename; to save all defnitions in a fle
load flename; to load all defnitions from a fle
delete funname; to delete the defnition corresponding to the function named funname

THIS IS ALL I HAVE SO FAR. PLZ HELP ME OUT. FOLLOWING ARE THE DETAILS THROUGH WHICH IT IS REQUIRED TO BE DONE.

A function is a labelled tree
It is a tree with a name
It also contains unbound variables, i.e. the variables listed in the
parameter list (and only those ones)
When a function is used, it is necessary to bound the variables to
actual values, and then evaluate the tree as any other numerical
expression

AND THE REQUIREMENTS ARE

show prints all deﬁnitions on screen
save ﬁlename saves all deﬁnitions in a ﬁle
load ﬁlename loads all deﬁnitions from a ﬁle
delete funname deletes the deﬁnition corresponding to the function
named funname